FreeBSD 7.0 manual page repository

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accf_http - buffer incoming connections until a certain complete HTTP

 

NAME

      accf_http - buffer incoming connections until a certain complete HTTP
      requests arrive
 

SYNOPSIS

      options INET
      options ACCEPT_FILTER_HTTP
      kldload accf_http
 

DESCRIPTION

      This is a filter to be placed on a socket that will be using accept() to
      receive incoming HTTP connections.
 
      It prevents the application from receiving the connected descriptor via
      accept() until either a full HTTP/1.0 or HTTP/1.1 HEAD or GET request has
      been buffered by the kernel.
 
      If something other than a HTTP/1.0 or HTTP/1.1 HEAD or GET request is
      received the kernel will allow the application to receive the connection
      descriptor via accept().
 
      The utility of accf_http is such that a server will not have to context
      switch several times before performing the initial parsing of the
      request.  This effectively reduces the amount of required CPU utilization
      to handle incoming requests by keeping active processes in preforking
      servers such as Apache low and reducing the size of the file descriptor
      set that needs to be managed by interfaces such as select(), poll() or
      kevent() based servers.
 
      The accf_http kernel option is also a module that can be enabled at run‐
      time via kldload(8) if the INET option has been compiled into the kernel.
 

EXAMPLES

      Assuming ACCEPT_FILTER_HTTP has been included in the kernel config file
      or the accf_http module has been loaded, this will enable the http accept
      filter on the socket sok.
 
              struct accept_filter_arg afa;
 
              bzero(&afa, sizeof(afa));
              strcpy(afa.af_name, "httpready");
              setsockopt(sok, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa));
      setsockopt(2), accept_filter(9)
 

HISTORY

      The accept filter mechanism and the accf_http filter were introduced in
      FreeBSD 4.0.
 

AUTHORS

      This manual page and the filter were written by Alfred Perlstein.
 

Sections

Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.